Toner compositions may be prepared by numerous processes, including emulsion aggregation (EA). Emulsion aggregation techniques may involve a batch or semi-continuous emulsion polymerization, as disclosed in, for example, U.S. Pat. No. 5,853,943, the entire disclosure of which is totally incorporated herein by reference.
Polyester toners may be prepared using amorphous and crystalline polyester resins as described, for example, in U.S. Pat. No. 7,547,499, the entire disclosure of which is totally incorporated herein by reference. The incorporation of these polyesters into the toner requires that they first be formulated into emulsions prepared by solvent containing batch processes, such as solvent flash emulsification and/or solvent-based phase inversion emulsification (PIE). The emulsion from the PIE process and other ingredients may be incorporated into the toner particles via an aggregation step, followed by a coalescence step at an elevated temperature.
The mean particle size (D50v) is an important characteristic of the emulsion produced from the PIE process, because the emulsion particle size affects toner slurry viscosity and the toner aggregation rate. Batches having slightly lower or slightly higher than desired particle sizes can be blended with other batches for use in the toner process. However, scrap manufacturing batches having “out-of spec” particle sizes must be disposed of properly, which is costly and bad for the environment.